Power storage module and fixing structure of power storage module

ABSTRACT

A power storage module that has a plurality of power storage cells stacked in a stacking direction, a pair of insulating end power storage cell holders superimposed at opposite ends in the stacking direction, and a pair of end plates superimposed at opposite ends in the stacking direction of the end power storage cell holders. In a mounted state, a lower end in a vertical direction of the end power storage cell holder projects downward from lower ends in a vertical direction of the power storage cell and the end plate. The end power storage cell holder includes a first face opposing the end plate and a second face opposing the power storage cell. A first drainage channel is formed on the first face and extends vertically downwardly and bends outward in the stacking direction. A second drainage passage extends vertically and is formed on the second face.

TECHNICAL FIELD

The present invention relates to a power storage module that includes aplurality of power storage cells stacked in a stacking direction, a pairof insulating end power storage cell holders superimposed at oppositeends in the stacking direction of the power storage cells, and a pair ofend plates superimposed at opposite ends in the stacking direction ofthe end power storage cell holders, and to a fixing structure of thepower storage module.

BACKGROUND ART

Such a power storage module is known from Patent Document 1 below.

RELATED ART DOCUMENTS Patent Documents

Patent Document 1: Japanese Patent Application Laid-open No. 2012-014962

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

In such a power storage module, since a power storage cell or an endplate has a relatively large heat capacity, moisture in air condenseswhen the temperature is low, and condensed water is easily formed.Condensed water generated in the power storage cell is sometimesconnected to an electrode and the water is given a potential(hereinafter, called galvanic water), and condensed water generated onthe end plate, which has no electrode, is water that is not given apotential (hereinafter, called non-galvanic water). This non-galvanicwater becomes galvanic water after coming into contact with the galvanicwater, a liquid junction is formed between the electrode of the powerstorage cell and the end plate via the galvanic water, and there is apossibility of a short circuit between the end plate and a vehicle bodyframe.

The present invention has been accomplished in light of the abovecircumstances, and it is an object thereof to prevent a liquid junctionbetween a power storage cell and an end plate from being formed viacondensed water.

Means for Solving the Problems

In order to attain the above object, according to a first aspect of thepresent invention, there is provided a power storage module comprising aplurality of power storage cells stacked in a stacking direction, a pairof insulating end power storage cell holders superimposed at oppositeends in the stacking direction of the power storage cells, and a pair ofend plates superimposed at opposite ends in the stacking direction ofthe end power storage cell holders, wherein in a mounted state, a lowerend in a vertical direction of the end power storage cell holderprojects downwardly from lower ends in a vertical direction of the powerstorage cell and the end plate, the end power storage cell holdercomprises a first face opposing the end plate and a second face opposingthe power storage cell, a first drainage channel is formed on the firstface, the first drainage channel extending vertically downwardly andthen bending outwardly in the stacking direction, and a second drainagepassage extending vertically is formed on the second face.

Further, according to a second aspect of the present invention, inaddition to the first aspect, a guide rib projecting outwardly in thestacking direction is formed on a periphery of the first face, and thefirst drainage channel is connected to an inner side of the guide rib.

Furthermore, according to a third aspect of the present invention, inaddition to the second aspect, a section, bending outwardly in thestacking direction, of the first drainage channel is inclined so that adownstream side is low.

Moreover, according to a fourth aspect of the present invention, inaddition to the second or third aspect, the guide rib of the end powerstorage cell holder comprises a separating portion surrounding afastening portion of a frame providing a connection between the pair ofend plates, and a cutout providing communication between an inside andan outside of the guide rib is formed in the separating portion.

Further, according to a fifth aspect of the present invention, there isprovided a fixing structure of a power storage module for fixing thepower storage module according to any one of the first to fourth aspectson a support plate, wherein an edge of the support plate is positionedbetween an outlet of the first drainage channel and an outlet of thesecond drainage channel, and the edge is at a height that is lower thanthe height of the outlet of the first drainage channel and higher thanthe height of the outlet of the second drainage channel.

Furthermore, according to a sixth aspect of the present invention, inaddition to the fifth aspect, a seal member is disposed between the edgeof the support plate and the end power storage cell holder.

Moreover, according to a seventh aspect of the present invention, inaddition to the fifth or sixth aspect, the support plate is inclined sothat the first drainage channel side is lower than the second drainagechannel side.

A first guide rib 12 h and a second guide rib 12 i of an embodimentcorrespond to the guide rib of the present invention, and an upper frame15 and a lower frame 16 of the embodiment correspond to the frame of thepresent invention.

Effects of the Invention

In accordance with the first aspect of the present invention, the powerstorage module is formed by layering a pair of insulating end powerstorage cell holders over opposite ends, in the stacking direction, ofthe plurality of power storage cells stacked in the stacking direction,and layering a pair of end plates over opposite ends of the end powerstorage cell holders in the stacking direction. In a state in which thepower storage module is mounted, the end power storage cell holder,whose lower end in the vertical direction projects downwardly from thelower end, in the vertical direction, of the power storage cell and theend plate, includes the first face opposing the end plate and the secondface opposing the power storage cell. Since the first drainage channelextending downwardly in the vertical direction and then bendingoutwardly in the stacking direction is formed on the first face, and thesecond drainage passage extending in the vertical direction is formed onthe second face, it is possible to separately discharge non-galvanicwater on the first face side and galvanic water on the second face sidevia the first drainage channel and the second drainage channelrespectively so that they do not make contact with each other, therebypreventing a liquid junction from being formed between the power storagecell and the end plate.

Furthermore, in accordance with the second aspect of the presentinvention, since the guide rib projecting outwardly in the stackingdirection is formed on the periphery of the first face, and the firstdrainage channel is connected to the inside of the guide rib, it ispossible to reliably discharge non-galvanic water on the first face tothe first drainage channel, thereby preventing the non-galvanic waterfrom leaking from the first face side to the second face side andcontacting the galvanic water.

Moreover, in accordance with the third aspect of the present invention,since the part, bending outwardly in the stacking direction, of thefirst drainage channel is inclined so that the downstream side becomeslow, it is possible to smoothly discharge the non-galvanic water of thefirst drainage channel, thereby reliably preventing it from contactingthe galvanic water of the second drainage channel.

Furthermore, in accordance with the fourth aspect of the presentinvention, since the guide rib of the end power storage cell holderincludes the separating part surrounding the fastening portion of theframe for making the pair of end plates contact each other, it ispossible to smoothly discharge condensed water formed on the surface ofthe frame to the first drainage channel, through which non-galvanicwater flows, thus preventing the condensed water from flowing into thesecond drainage channel, through which galvanic water flows, andpreventing the frame from forming a liquid junction.

Moreover, in accordance with the fifth aspect of the present invention,since the edge of the support plate is positioned between the outlet ofthe first drainage channel and the outlet of the second drainagechannel, and the edge is at a height that is lower than the height ofthe outlet of the first drainage channel and higher than the height ofthe outlet of the second drainage channel, it becomes difficult forgalvanic water discharged from the outlet of the second drainage channelto flow beyond the edge of the support plate and contact non-galvanicwater discharged from the outlet of the first drainage channel, therebyreliably preventing a liquid junction from being formed due to contactbetween the galvanic water and the non-galvanic water.

Furthermore, in accordance with the sixth aspect of the presentinvention, since the seal member is disposed between the edge of thesupport plate and the end power storage cell holder, it is possible tomore reliably prevent contact between the non-galvanic water on thefirst drainage channel side and the galvanic water on the seconddrainage channel side.

Moreover, in accordance with the seventh aspect of the presentinvention, since the support plate is tilted so that the first drainagechannel side is lower than the second drainage channel side, it ispossible to prevent condensed water that has dropped from the firstdrainage channel onto the support plate from flowing back toward thesecond drainage channel side, thus more reliably preventing a liquidjunction from being formed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a power storage module. (firstembodiment)

FIG. 2 is an exploded perspective view of the power storage module.(first embodiment)

FIG. 3 is a perspective view of a power storage pack. (first embodiment)

FIG. 4 is a view in the direction of arrow 4 in FIG. 1. (firstembodiment)

FIG. 5 is a view in the direction of arrow 5 in FIG. 1. (firstembodiment)

FIG. 6 is a view in the direction of arrow 6 in FIG. 4. (firstembodiment)

FIG. 7 is a sectional view along line 7-7 in FIG. 6. (first embodiment)

FIG. 8 is a view from arrowed line 8-8 in FIG. 4. (first embodiment)

FIG. 9 is a sectional view along line 9-9 in FIG. 8. (first embodiment)

FIG. 10 is a view in the direction of arrow 10 in FIG. 5. (firstembodiment)

FIG. 11 is a view in the direction of arrow 11 in FIG. 5. (firstembodiment)

EXPLANATION OF REFERENCE NUMERALS AND SYMBOLS

-   11 Power storage cell-   12A End power storage cell holder-   12B End power storage cell holder-   12 h First guide rib (guide rib)-   12 i Second guide rib (guide rib)-   14 End plate-   15 Upper frame (frame)-   15 a Fastening portion-   16 Lower frame (frame)-   16 a Fastening portion-   29 Support plate-   30 Seal member-   31 First drainage channel-   31 a Outlet-   32 Second drainage channel-   32 a Outlet-   M Power storage module-   P1 First face-   P2 Second face-   a Separating part-   β Cutout

MODES FOR CARRYING OUT THE INVENTION

A mode for carrying out the present invention is explained below byreference to FIG. 1 to FIG. 11.

First Embodiment

As shown in FIG. 1 and FIG. 2, a power storage module M, which is usedas a power supply device for an electric automobile or a hybridautomobile, includes a predetermined number (12 in the embodiment) ofpower storage cells 11 that are stacked in a stacking direction. Eachpower storage cell 11 formed from for example a lithium ion battery isformed into a rectangular parallelepiped and includes a pair of mutuallyopposing main faces 11 a and 11 a, a pair of mutually opposing sidefaces 11 b and 11 b perpendicular to the main faces 11 a and 11 a, andmutually opposing top face 11 c and bottom face 11 d perpendicular tothe main faces 11 a and 11 a and the side faces 11 b and 11 b, positiveand negative electrodes 11 e and 11 e being provided on the top face 11c.

The pair of main faces 11 a and 11 a and the pair of side faces 11 b and11 b of each power storage cell 11 are covered by acondensation-preventing sheet made of a synthetic resin, thus making itdifficult for condensed water to be formed on the surface of the powerstorage cell 11, which is made of metal. However, the top face 11 c andthe bottom face 11 d of each power storage cell 11 are not covered by acondensation-preventing sheet, and the metal surface is exposed.

In the present specification, a direction that is perpendicular to thestacking direction and joins the top face 11 c and the bottom face 11 dof the power storage cell 11 is defined as the up-and-down direction,and a direction that is perpendicular to the stacking direction andjoins the pair of side faces 11 b and 11 b of the power storage cell 11is defined as the left-and-right direction.

The main faces 11 a of twelve of the power storage cells 11 and elevenrectangular plate-shaped intermediate power storage cell holders 12,made of a synthetic resin, are superimposed in turn in the stackingdirection, a pair of rectangular plate-shaped end power storage cellholders 12A and 12B, made of a synthetic resin, are superimposed onouter sides, in the stacking direction, of the two power storage cells11 and 11 at opposite ends in the stacking direction, and a pair of endplates 14 and 14, made of metal, are further superimposed on outer sidesthereof in the stacking direction. The eleven intermediate power storagecell holders 12 are members having an interchangeable identical shape,and the pair of end power storage cell holders 12A and 12B are membershaving shapes that are different from that of the intermediate powerstorage cell holders 12 and having mutually different shapes.

In a state in which the power storage cells 11, the intermediate powerstorage cell holders 12, the end power storage cell holders 12A and 12B,and the end plates 14 and 14 are stacked in the stacking direction, fourcorners of the pair of end plates 14 and 14 are linked to each other bymeans of upper frames 15 and 15 formed from a pair of rod-shaped membersmade of metal and having an L-shaped cross section, and lower frames 16and 16 formed from a pair of rod-shaped members made of metal and havingan L-shaped cross section, thus carrying out assembly of the powerstorage module M. That is, the power storage module M is assembled byabutting thick fastening portions 15 a provided at opposite ends of theupper frames 15 and 15 and thick fastening portions 16 a provided atopposite ends of the lower frames 16 and 16 against the four corners ofthe end plates 14 and 14, and screwing bolts 17 extending through theend plates 14 and 14 into the fastening portions 15 a, 16 a.

In this arrangement, in order to prevent condensed water from forming aliquid junction between the power storage cells 11 and the upper frames15 and 15, upper insulators 18 and 18, made of a synthetic resin, aredisposed between the upper frames 15 and 15 and the power storage cells11, intermediate power storage cell holders 12, and end power storagecell holders 12A and 12B. Similarly, in order to prevent condensed waterfrom forming a liquid junction between the power storage cells 11 andthe lower frames 16, lower insulators 19 and 19, made of a syntheticresin, are disposed between the lower frames 16 and 16 and the powerstorage cells 11, intermediate power storage cell holders 12, and endpower storage cell holders 12A and 12B. Furthermore, plate springs 20and 20 for preventing the occurrence of rattling by pushing the bottomfaces 11 d of the power storage cells 11 upward are disposed between thelower frames 16 and 16 and the lower insulators 19 and 19.

Each of the intermediate power storage cell holders 12 and the end powerstorage cell holders 12A and 12B includes a plate-shaped plate portion12 a, four engagement portions 12 b projecting in the stacking directionfrom four corners of the plate portion 12 a, a thermistor retainingportion 12 c provided in a middle part at the lower end of the plateportion 12 a, and a plate-shaped shielding portion 12 d projecting inthe stacking direction from a middle part in the left-and-rightdirection of the upper edge of the plate portion 12 a. However, the endpower storage cell holder 12A alone on one end side in the stackingdirection does not include the thermistor retaining portion 12 c, andthe end power storage cell holder 12B alone on the other end side in thestacking direction does not include the shielding portion 12 d.

As shown in FIG. 2, FIG. 10, and FIG. 11, the thermistor retainingportions 12 c of the intermediate power storage cell holders 12 and theother end power storage cell holder are linked to each other due toengagement between pins 12 e and pin holes 12 f, a thermistor 21A isfitted into the thermistor retaining portion 12 c of the intermediatepower storage cell holder 12 positioned at one end in the stackingdirection, the thermistor 21A measuring temperature by being in contactwith the bottom face 11 d of the power storage cell 11 positioned atsaid one end in the stacking direction, and a thermistor 21B is fittedinto the thermistor retaining portion 12 c of the end power storage cellholder 12B positioned at the other end in the stacking direction, thethermistor 21B measuring temperature by being in contact with the bottomface 11 d of the power storage cell 11 positioned at said other end inthe stacking direction.

Harnesses 22 and 22 extending from the thermistor 21A are retained inthe interior of a harness holder 24 formed into a sheath shape from asynthetic resin. The harnesses 22 and 22 of the thermistor 21A extendingfrom the other end side in the stacking direction of the harness holder24 are superimposed on the other thermistor 21B, a total of fourharnesses 22 of the thermistors 21A and 21B being bound there andcovered by a harness cover 25. A connector 26 provided at tips of thefour harnesses 22 coming out from the harness cover 25 is connected toan electronic control unit 27 (see FIG. 5) provided on the other endplate 14.

As shown in FIG. 1 and FIG. 4, among the top faces 11 c of the twelvepower storage cells 11, the intermediate part in the left-and-rightdirection is covered by the shielding portions 12 d of the intermediatepower storage cell holders 12 and the end power storage cell holder 12A,and opposite end parts in the left-and-right direction, from which theelectrodes 11 e project, are covered by a bus bar plate 28 formed into aU-shape from an insulating material. The bus bar plate 28 has a metalplate that electrically connects in series the electrodes 11 e of thetwelve power storage cells 11.

As shown in FIG. 3, six of the power storage modules M are supported onone support plate 29, made of metal, to thus form a power storage packP. In this arrangement, the power storage modules M are arranged in anattitude in which they are tilted through 90° so that the left-and-rightdirection becomes the vertical direction, and upper faces thereof onwhich the bus bar plates 28 are provided face opposite directions inturn. Six rectangular openings 29 a are formed in the support plate 29so as to oppose one of left and right side faces of the six powerstorage modules M, and an annular seal member 30 formed from an elasticmember such as a foam rubber is disposed on the periphery of eachopening 29 a. In a vehicle-mounted state as shown in FIG. 3, theleft-and-right direction defined for FIG. 1 and FIG. 2 becomes thevertical direction, and the up-and-down direction defined for FIG. 1 andFIG. 2 becomes the horizontal direction.

As shown in FIG. 2, FIG. 4, and FIG. 6 to FIG. 8, the upper insulator 18is a member molded as a unit from a synthetic resin, and its constantcross section in the stacking direction includes a first wall portion 18a, a second wall portion 18 b, a third wall portion 18 c, a fourth wallportion 18 d, and a fifth wall portion 18 e (see FIG. 7); a verticalwall 15 b, which is vertical in a vehicle-mounted state, of the upperframe 15 having an L-shaped cross section is covered by the first wallportion 18 a, the second wall portion 18 b, and the third wall portion18 c, and an upper face of a horizontal wall 15 c, which is horizontalin the vehicle-mounted state, of the upper frame 15 is covered by thefourth wall portion 18 d. The extremity of the fifth wall portion 18 e,which extends downwardly from the fourth wall portion 18 d in thevertical direction in the vehicle-mounted state, bends in a zig-zagmanner.

Furthermore, a large number of first ribs 18 f, which extend verticallyin the vehicle-mounted state, are formed in parallel on an outer face,which extends substantially flush with the top faces 11 c of the powerstorage cells 11, of the first wall portion 18 a, and a plurality ofsecond ribs 18 g providing a connection between two adjacent first ribs18 f and 18 f are formed into a V-shape on the outer face. The secondribs 18 g of the upper frame 15 positioned on the upper side in thevertical direction in the vehicle-mounted state are disposed in aninverted V-shape, but the second ribs 18 g of the upper frame 15positioned on the lower side in the vertical direction in thevehicle-mounted state are disposed in a V-shape (see FIG. 4).

Furthermore, a lower face of the horizontal wall 15 c of the upper frame15 positioned on the lower side in the vertical direction in thevehicle-mounted state and the lower end, in the vertical direction, ofthe first wall portion 18 a of the upper insulator 18 positioned on thelower side in the vertical direction in the vehicle-mounted state opposean upper face of the support plate 29, and the lower end, in thevertical direction, of the fifth wall portion 18 e of the upperinsulator 18 positioned on the lower side in the vertical direction inthe vehicle-mounted state extends downwardly beyond the edge of theopening 29 a of the support plate 29. In this arrangement, the sealmember 30 is held between the lower face of the horizontal wall 15 c ofthe upper frame 15 and the edge of the opening 29 a of the support plate29 (see FIG. 7). As shown in FIG. 7, the lower end of the first wallportion 18 a is positioned on the lower side in the vertical directionrelative to the lower face of the horizontal wall 15 c of the upperframe 15.

As shown in FIG. 2, FIG. 5, FIG. 6, and FIG. 8, the lower insulator 19includes a first wall portion 19 a extending along the bottom faces 11 dof the power storage cells 11, a second wall portion 19 b rising fromthe first wall portion 19 a and extending along the side faces 11 b ofthe power storage cells 11, and a third wall portion 19 c rising fromthe second wall portion 19 b and extending in a direction away from theside faces 11 b of the power storage cells 11, the extremity of thethird wall portion 19 c bending in a zig-zag manner.

The third wall portion 19 c of the lower insulator 19 and the fifth wallportion 18 e of the upper insulator 18 have an identical shape (see FIG.6) and are positioned in parallel to each other with a predetermined gapalong the stacking direction. Therefore, in the same way as for thefifth wall portion 18 e of the upper insulator 18, in thevehicle-mounted state the lower end, in the vertical direction, of thethird wall portion 19 c of the lower insulator 19 extends downwardlybeyond the edge of the opening 29 a of the support plate 29, and theseal member 30 is held between a lower face of the horizontal wall 16 cof the lower frame 16 (see FIG. 8) and the edge of the opening 29 a ofthe support plate 29.

First wall portions 12 g and 12 g project from left and right end partsof the end power storage cell holders 12A and 12B, and extremities ofthe first wall portions 12 g and 12 g bend in a zig-zag manner. Thefifth wall portion 18 e of the upper insulator 18, the third wallportion 19 c of the lower insulator 19, and the first wall portions 12 gand 12 g of the end power storage cell holders 12A and 12B are connectedto each other to thus form a rectangular frame (see FIG. 6), and in thevehicle-mounted state the lower end, in the vertical direction, of therectangular frame extends downwardly beyond lower ends, in the verticaldirection, of the power storage cells 11 and the end plates 14 and 14and beyond the edge of the opening 29 a of the support plate 29.

As shown in FIG. 5, FIG. 10, and FIG. 11, opposite end parts in theleft-and-right direction of the bottom faces 11 d of the power storagecells 11 forming the power storage module M are completely covered bythe first wall portions 19 a and 19 a of the pair of the lowerinsulators 19 and 19, and a section sandwiched by the pair of first wallportions 19 a and 19 a is partially covered by the thermistor retainingportions 12 c of the intermediate power storage cell holders 12 and theend power storage cell holder 12B on said other end side. A firstpartition wall 19 d bending in a zig-zag manner in the left-and-rightdirection and extending in the stacking direction is projectinglyprovided on a lower face of the first wall portion 19 a. In thevehicle-mounted state in which the bottom faces 11 d of the powerstorage cells 11 face the vertical direction (see FIG. 5), the firstpartition wall 19 d, which bends in a zig-zag manner, attains a shape inwhich a large number of V shapes are connected.

As shown in FIG. 5, FIG. 10, and FIG. 11, second partition walls 12 jand 12 j project downwardly from lower ends of the pair of end powerstorage cell holders 12A and 12B. The second partition walls 12 j and 12j of the end power storage cell holders 12A and 12B form a rectangularframe in cooperation with the first partition walls 19 d and 19 d of thepair of the lower insulators 19 and 19, and this frame surrounds theperiphery of the thermistor retaining portions 12 c of the intermediatepower storage cell holders 12 and the end power storage cell holder 12Bon said other end side.

As shown in FIG. 8 and FIG. 9, the end power storage cell holder 12A onsaid one side includes a pair of first guide ribs 12 h and 12 h and apair of second guide ribs 12 i and 12 i surrounding the plate portion 12a. The pair of first guide ribs 12 h and 12 h extend along the pair ofside faces 11 b and 11 b of the power storage cells 11, separating partsa at opposite ends thereof curving into an arc-shape curve so as to moveaway from the fastening portions 15 a 15 a, 16 a, 16 a of the upperframes 15 and 15 and the lower frames 16 and 16. The pair of secondguide ribs 12 i and 12 i extend along the top face 11 c and the bottomface 11 d of the power storage cells 11, and opposite ends thereof aresuperimposed on opposite ends of the pair of first guide ribs 12 h and12 h via a cutout β. Two guide parts b extend from part of each of thepair of first guide ribs 12 h and 12 h extending along the pair of sidefaces 11 b and 11 b of the power storage cells 11, the guide parts bextending in directions in which they approach each other.

A first drainage channel 31 is formed on a first face P1, on the endplate 14 side, of the end power storage cell holder 12A (see FIG. 9). Inthe vehicle-mounted state, the first drainage channel 31 extendsdownwardly in the vertical direction along the plate portion 12 a of theend power storage cell holder 12A, and the lower end thereof is bentthrough 90° in a substantially horizontal direction by means of thefirst guide rib 12 h. In this arrangement, the first guide rib 12 h isinclined with respect to the horizontal direction so that the extremityside is slightly lower. On the other hand, a second drainage channel 32is formed on a second face P2, on the power storage cells 11 side, ofthe end power storage cell holder 12A (see FIG. 9). In thevehicle-mounted state, the second drainage channel 32 extends downwardlyin the vertical direction along the plate portion 12 a of the end powerstorage cell holder 12A.

The edge of the opening 29 a of the support plate 29 is positionedbetween an outlet 31 a of the first drainage channel 31 and an outlet 32a of the second drainage channel 32, and the edge is set so as to be ata height that is lower than the height of the outlet 31 a of the firstdrainage channel 31 and higher than the height of the outlet 32 a of thesecond drainage channel 32. Furthermore, the support plate 29 isinclined so that the first drainage channel 31 side is slightly lowerthan the second drainage channel 32 side. The seal member 30 is disposedbetween the edge of the opening 29 a of the support plate 29 and thelower face of the first guide rib 12 h. The seal member 30 is originallyfor preventing the leakage of cooling air for cooling the power storagecells 11, but in the present embodiment it exhibits a function ofpreventing the leakage of condensed water in addition to the abovefunction.

The structure of the end power storage cell holder 12A on one side isexplained above, but the structure of the end power storage cell holder12B on the other side is substantially the same.

The operation of the embodiment of the present invention having theabove arrangement is now explained.

Among the surfaces of the power storage cells 11 forming the powerstorage module M, the main faces 11 a and 11 a and the side faces 11 band 11 b are covered by the condensation-preventing sheet and it istherefore relatively difficult for condensed water to form thereon, butthe top face 11 c and the bottom face 11 d are not covered by thecondensation-preventing sheet, and it is therefore relatively easy forcondensed water to form. When galvanic water whose potential has beenincreased by contacting the electrodes 11 e of the power storage cells11 forms a liquid junction with the upper frames 15 and 15 or the lowerframes 16 and 16, there is a possibility that current will flow from theupper frames 15 and 15 or the lower frames 16 and 16 to the vehicle bodyvia the end plates 14 and 14, and it is therefore necessary to suppressthe formation of a liquid junction between the power storage cells 11and the upper frames 15 and 15 and lower frames 16 and 16 or between thepower storage cells 11 and the end plates 14 and 14.

Since the intermediate power storage cell holders 12, which are made ofa synthetic resin, are disposed between adjacent power storage cells 11,the end power storage cell holders 12A and 12B, which are made of asynthetic resin, are disposed between the power storage cells 11 and theend plates 14 and 14, the upper insulators 18 and 18, which are made ofa synthetic resin, are disposed between the power storage cells 11 andthe upper frames 15 and 15, and the lower insulators 19 and 19, whichare made of a synthetic resin, are disposed between the power storagecells 11 and the lower frames 16 and 16, the formation of a liquidjunction can be suppressed to some extent by means of these syntheticresin members, but it is necessary to take measures assuming a case inwhich a large quantity of condensed water is formed.

Since the power storage module M is mounted on a vehicle in manner inwhich it is tilted through 90° such that one of the side faces 11 b ofthe power storage cells 11 faces downward in the vertical direction, itis important to provide electrical shielding between, among the pair ofupper frames 15 and 15 and the pair of the lower frames 16 and 16, theupper frame 15 and lower frame 16 that are on the lower side in thevehicle-mounted state and the upper insulator 18 and lower insulator 19e on the lower side in the vertical direction, which cover them.

Among the surfaces of each power storage cell 11, it is easy forcondensed water to form on the top face 11 c and the bottom face 11 d,which are non-covered portions that are not covered by thecondensation-preventing sheet, but since the top face 11 c of the powerstorage cell 11 is covered by the shielding portion 12 d of theintermediate power storage cell holder 12 or the end power storage cellholder 12B and the bus bar plate 28, a majority of the bottom face 11 dof the power storage cell 11 is covered by the first wall portions 19 aand 19 a of the pair of the lower insulators 19 and 19, and the openingsa of the thermistor retaining portions 12 c of the intermediate powerstorage cell holders 12 into which the thermistors 21A and 21B are notfitted are only slightly open, by carrying out thermal insulation bycovering the top face 11 c and the bottom face 11 d, on which condensedwater easily forms, as much as possible, the formation of condensedwater can be minimized and a liquid junction can be prevented from beingformed (see FIG. 10 and FIG. 11).

Furthermore, if the peripheries of the power storage cells 11 arecompleted sealed, there is a possibility that a liquid junction will beformed between the power storage cells 11 themselves as a result of justa small amount of condensed water being formed, but due to part of thebottom wall 11 d being exposed by means of the opening α of thethermistor retaining portion 12 c, condensed water formed on the powerstorage cell 11 can be discharged to the outside via the opening α,thereby preventing a liquid junction from being formed between the powerstorage cells 11 due to condensed water.

Moreover, there is a possibility that a liquid junction will be formedif condensed water flowing out from the opening α makes the lower frame16 beneath it in the vertical direction become wet, but since the firstpartition wall 19 d projects, in a canopy shape, from the first wallportion 19 a of the lower insulator 19 connected to the underneath ofthe opening α, it is possible to prevent the lower frame 16 frombecoming wet due to the condensed water to thus form a liquid junction.Furthermore, since the pair of end power storage cell holders 12A and12B include the second partition walls 12 j and 12 j, which surround theopening α in cooperation with the first partition walls 19 d and 19 d ofthe lower insulators 19 and 19, it is possible by means of the secondpartition walls 12 j and 12 j to reliably prevent condensed water thathas flowed out from the opening α from being formed liquid junction withthe end plates 14 and 14 (see FIG. 10 and FIG. 11).

When condensed water formed on the top faces 11 a of the power storagecells 11 flows downwardly in the vertical direction and reaches thefirst wall portion 18 a of the upper insulator 18, since the largenumber of first ribs 18 f, which extend vertically, are formed on thesurface of the first wall portion 18 a, condensed water is guideddownwardly by the first ribs 18 f and prevented from flowing toward theend plates 14 and 14 side along the upper insulator 18, therebypreventing a liquid junction from being formed between the power storagecells 11 and the end plates 14 and 14 via the upper insulator 18 (seeFIG. 6).

Condensed water guided downwardly by means of the first ribs 18 f istemporarily retained by the V-shaped second ribs 18 g, and condensedwater temporarily builds up between the first ribs 18 f and the secondribs 18 g; after a fixed amount of condensed water has built up it dropsdownward, thus making it difficult to form uninterrupted condensedwater, electrical contact between the power storage cells 11 and acomponent made of metal that is present in the vicinity thereof (forexample, the support plate 29) via uninterrupted condensed water isprevented, and as a result the formation of a liquid junction can beprevented. Moreover, since condensed water formed on the power storagecells 11 flows downwardly along the upper insulator 18, it is alsopossible to prevent effectively a liquid junction from being formedbetween the power storage cells 11 due to the condensed water.

Furthermore, the fifth wall portion 18 e of the upper insulator 18, thethird wall portion 19 c of the lower insulator 19, and the pair of firstwall portions 12 g and 12 g of the pair of end power storage cellholders 12A and 12B are disposed as a rectangular frame-shaped wallinside the space bounded by the upper frame 15, the lower frame 16, andthe pair of end plates 14 and 14. Since the lower end of the wallextends further downwardly in the vertical direction than the lower endsof the upper frame 15, the lower frame 16, and the pair of end plates 14and 14, it is possible to prevent effectively condensed water flowingdownwardly from the power storage cells 11 from contacting the upperframe 15, the lower frame 16, and the pair of end plates 14 and 14 (seeFIG. 6).

Moreover, since the lower edges of the fifth wall portion 18 e of theupper insulator 18, the third wall portion 19 c of the lower insulator19, and the pair of first wall portions 12 g and 12 g of the pair of endpower storage cell holders 12A and 12B bend in a zig-zag shape, it ispossible to make the drainage of condensed water good, therebypreventing further effectively a liquid junction from being formedbetween the power storage cells 11 and the upper frame 15, lower frame16, and end plates 14 and 14.

Furthermore, the power storage module M is supported on the opening 29 aof the support plate 29, and since the lower edges of the fifth wallportion 18 e of the upper insulator 18, the third wall portion 19 c ofthe lower insulator 19, and the pair of first wall portions 12 g and 12g of the pair of end power storage cell holders 12A and 12B extendthrough the opening 29 a of the support plate 29 downwardly in thevertical direction, it is possible to prevent condensed water fromcontacting the support plate 29, thereby preventing the formation of aliquid junction via the support plate 29 (see FIG. 8).

Furthermore, condensed water formed on the surface of the end plate 14becomes attached to the first discharge path 31 along the first face P1,opposing the end plate 14, of the end power storage cell holder 12A, andcondensed water formed on the surface of the power storage cells 11becomes attached to the second discharge path 32 along the second faceP2, opposing the power storage cells 11, of the end power storage cellholder 12A. The former condensed water is non-galvanic water, whereasthe latter condensed water is galvanic water; if the two are mixed, theentirety becomes galvanic water, and a liquid junction easily forms,therefore making it necessary to block the mixing thereof.

The first drainage channel 31 formed on the first face P1 of the endpower storage cell holder 12A extends downwardly in the verticaldirection and then bends outwardly in the stacking direction, whereasthe second drainage passage 32 formed on the second face P2 of the endpower storage cell holder 12A extends downwardly in the verticaldirection in a straight manner, and it is therefore possible toseparately discharge the non-galvanic water of the first drainagechannel 31 and the galvanic water of the second drainage passage 32 sothat they do not contact each other, thereby preventing a liquidjunction from being formed between the power storage cells 11 and theend plate 14 (see FIG. 9).

Furthermore, since the first and second guide ribs 12 h, 12 h, 12 i, 12i projecting outwardly in the stacking direction are formed on theperiphery of the first face P1, and the first drainage channel 31 isconnected to the inside thereof, it is possible to reliably dischargenon-galvanic water on the first face P1 to the first drainage channel31, thereby preventing the non-galvanic water from leaking from thefirst face P1 side to the second face P2 side and contacting thegalvanic water. In this arrangement, since the part of the firstdrainage channel 31 that bends outwardly in the stacking direction isinclined so that the downstream side is low, it is possible to smoothlydischarge the non-galvanic water of the first drainage channel 31,thereby preventing it from contacting the galvanic water of the seconddrainage channel 32 (see FIG. 8 and FIG. 9).

Moreover, since the first and second guide ribs 12 h and 12 h, 12 i, 12i of the end power storage cell holder 12A include the separating partsa surrounding the fastening portions 15 a, 15 a, 16 a, 16 a of the upperframes 15 and 15 and the lower frames 16 and 16 for connecting the pairof end plates 14 and 14 with each other, it is possible to smoothlydischarge condensed water formed on the surfaces of the upper frames 15and 15 and the lower frames 16 and 16 to the first drainage channel 31,through which non-galvanic water flows, thus preventing it from flowinginto the second drainage channel 32, through which galvanic water flows,and preventing the formation of a liquid junction between the upperframes 15 and 15 and lower frames 16 and 16 and the end plates 14 and14.

Furthermore, since the edge of the opening 29 a of the support plate 29is positioned between the outlet 31 a of the first drainage channel 31and the outlet 32 a of the second water channel 32, and the edge is at aheight that is lower than the height of the outlet 31 a of the firstdrainage channel 31 and higher than the height of the outlet 32 a of thesecond drainage channel 32, it becomes difficult for galvanic waterdischarged from the outlet 32 a of the second drainage channel 32 toflow beyond the edge of the opening 29 a of the support plate 29 andcontact non-galvanic water discharged from the outlet 31 a of the firstdrainage channel 31, thereby reliably preventing a liquid junction frombeing formed due to contact between the galvanic water and thenon-galvanic water (see FIG. 9).

Moreover, since the seal member 30 is disposed between the edge of theopening 29 a of the support plate 29 and the end power storage cellholder 12A, it is possible to more reliably prevent contact between thenon-galvanic water on the first drainage channel 31 side and thegalvanic water on the second drainage channel 32 side. Furthermore,since the support plate 29 is tilted so that the first drainage channel31 side is lower than the second drainage channel 32 side, it ispossible to prevent condensed water that has dropped from the firstdrainage channel 31 on the support plate 32 from flowing back toward thesecond drainage channel 32 side, thus preventing the formation of aliquid junction.

The operation of the end power storage cell holder 12A on one side isexplained above, but the operation of the end power storage cell holder12B on the other side is the same.

An embodiment of the present invention is explained above, but thepresent invention may be modified in a variety of ways as long as themodifications do not depart from the spirit and scope thereof.

For example, the power storage cell 11 of the embodiment is not limitedto a lithium ion battery and may be another type of battery orcapacitor.

Furthermore, the shape of the end power storage cell holders 12A and 12Bis not limited to that of the embodiment.

Moreover, in the embodiment condensed water is explained, but needlessto say the present invention is also effective with respect toelectrolyte that has leaked from the power storage cell 11 or water thathas entered from the outside.

1. A power storage module comprising: a plurality of power storage cellsstacked in a stacking direction; a pair of insulating end power storagecell holders superimposed at opposite ends in the stacking direction ofthe power storage cells; and a pair of end plates superimposed atopposite ends in the stacking direction of the end power storage cellholders, wherein in a mounted state, a lower end in a vertical directionof the end power storage cell holder projects downwardly from lower endsin a vertical direction of the power storage cell and the end plate, theend power storage cell holder comprises a first face opposing the endplate and a second face opposing the power storage cell, a firstdrainage channel is formed on the first face, the first drainage channelextending vertically downwardly and then bending outwardly in thestacking direction, and a second drainage passage extending verticallyis formed on the second face.
 2. The power storage module according toclaim 1, wherein a guide rib projecting outwardly in the stackingdirection is formed on a periphery of the first face, and the firstdrainage channel is connected to an inner side of the guide rib.
 3. Thepower storage module according to claim 2, wherein a section, bendingoutwardly in the stacking direction, of the first drainage channel isinclined so that a downstream side is low.
 4. The power storage moduleaccording to claim 2, wherein the guide rib of the end power storagecell holder comprises a separating portion surrounding a fasteningportion of a frame providing a connection between the pair of endplates, and a cutout providing communication between an inside and anoutside of the guide rib is formed in the separating portion.
 5. Afixing structure of a power storage module for fixing the power storagemodule according to claim 1 on a support plate, wherein an edge of thesupport plate is positioned between an outlet of the first drainagechannel and an outlet of the second drainage channel, and the edge is ata height that is lower than the height of the outlet of the firstdrainage channel and higher than the height of the outlet of the seconddrainage channel.
 6. The fixing structure of a power storage moduleaccording to claim 5, wherein a seal member is disposed between the edgeof the support plate and the end power storage cell holder.
 7. Thefixing structure of a power storage module according to claim 5, whereinthe support plate is inclined so that the first drainage channel side islower than the second drainage channel side.
 8. The power storage moduleaccording to claim 3, wherein the guide rib of the end power storagecell holder comprises a separating portion-surrounding a fasteningportion-of a frame-providing a connection between the pair of endplates, and a cutout providing communication between an inside and anoutside of the guide rib is formed in the separating portion.
 9. Afixing structure of a power storage module for fixing the power storagemodule-according to claim 2 on a support plate, wherein an edge of thesupport plate is positioned between an outlet of the first drainagechannel and an outlet of the second drainage channel, and the edge is ata height that is lower than the height of the outlet of the firstdrainage channel and higher than the height of the outlet of the seconddrainage channel.
 10. A fixing structure of a power storage module forfixing the power storage module-according to claim 3 on a support plate,wherein an edge of the support plate is positioned between an outlet ofthe first drainage channel and an outlet of the second drainage channel,and the edge is at a height that is lower than the height of the outletof the first drainage channel and higher than the height of the outletof the second drainage channel.
 11. A fixing structure of a powerstorage module for fixing the power storage module-according to claim 4on a support plate, wherein an edge of the support plate is positionedbetween an outlet of the first drainage channel and an outlet of thesecond drainage channel, and the edge is at a height that is lower thanthe height of the outlet of the first drainage channel and higher thanthe height of the outlet of the second drainage channel.
 12. The fixingstructure of a power storage module according to claim 6, wherein thesupport plate is inclined so that the first drainage channel side islower than the second drainage channel side.